叶形是影响陆地棉植株冠层结构和产量的重要农艺性状，同时还与光合效率密切相关，是棉花高光效育种研究的重点。陆地棉叶形根据叶裂深度可分为常态叶、亚鸡脚叶、鸡脚叶和超鸡脚叶，主要由D基因组L-D₁位点的等位基因调控，其对陆地棉叶片形态、冠层结构和光合产量的影响尚不清楚。本研究利用病毒诱导基因沉默技术（VIGS）及叶形参数分析发现L-D₁等位基因对叶形的调控具有基因剂量效应；打顶前，鲁棉研22亚鸡脚叶品系叶面积系数比常态叶品系分别减少8.54%和4.91%，打顶后分别减少8.48%和11.19%；中部冠层透光率打顶前后分别增加71.35%和134.88%，下部冠层透光率打顶前后分别增加123.14%和41.81%；鲁棉研28号遗传背景下，亚鸡脚叶系中部冠层透光率打顶前后分别增加38.88和93.10%，下部冠层透光率打顶前后分别增加28.15和118.62%。鲁棉研22亚鸡脚叶系净光合速率在大部分生育期内可提高0.93～12.45%，在鲁棉研28遗传背景下可提高7.12～13.84%。在两种遗传背景下，亚鸡脚叶品系的最终生物量比常态叶对照分别增加9.43和19.35%，产量也分别增加8.6和7.05%，且同时对纤维品质无不良影响。

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Chinese chive usually develops an off-flavor after a short storage time.  To explore effective ways to maintain the postharvest quality of Chinese chive, the effect of exogenous application of 6-benzylaminopurine (6-BA) on postharvest quality and antioxidant activity of chive was evaluated, and the mechanism of the physiological responses of chive to 6-BA treatment was explored.  Chives were sprayed for 10 min with 100, 300, or 500 mg L^–1 6-BA or with alkaline solution as the control, then stored at (2±1)°C with a relative humidity (RH) of 80–85%.  We found that 300 mg L^–1 6-BA significantly delayed yellowing and chlorophyll degradation, maintained the total phenolic and flavonoid content, and improved the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD).  In conclusion, we identified exogenous application of 6-BA as an effective method for maintaining postharvest quality of Chinese chive.  In addition, our finding that the activities of antioxidant enzymes increase in response to exogenous 6-BA provides new insights into the mechanism of cytokinin-based postharvest fresh-keeping. 

    A survey of the population densities of rice planthoppers is important for forecasting decisions and efficient control. Traditional manual surveying of rice planthoppers is time-consuming, fatiguing, and subjective. A new three-layer detection method was proposed to detect and identify white-backed planthoppers (WBPHs, Sogatella furcifera (Horváth)) and their developmental stages using image processing. In the first two detection layers, we used an AdaBoost classifier that was trained on a histogram of oriented gradient (HOG) features and a support vector machine (SVM) classifier that was trained on Gabor and Local Binary Pattern (LBP) features to detect WBPHs and remove impurities. We achieved a detection rate of 85.6% and a false detection rate of 10.2%. In the third detection layer, a SVM classifier that was trained on the HOG features was used to identify the different developmental stages of the WBPHs, and we achieved an identification rate of 73.1%, a false identification rate of 23.3%, and a 5.6% false detection rate for the images without WBPHs. The proposed three-layer detection method is feasible and effective for the identification of different developmental stages of planthoppers on rice plants in paddy fields.

Chinese farmers are often accused of overusing pesticides that play a crucial role in enhancing crop yield by reducing losses to crop pests. Pesticide overuse has caused a series of negative health and environmental externalities. This paper quantifies the productivity effect and the optimal amount of pesticides in rice, cotton and maize production in China from the economic perspective. Using survey data collected in 2012 and 2013, both Cobb-Douglas and Weibull damage control specifications are used to estimate the production function. Results show that pesticides have statistically significant productivity effect on crop yield. On the condition of Weibull damage control specifications, the marginal products of 1 kg of the active ingredients of pesticides for rice, cotton and maize are 71.06, 22.73 and 98.45 kg, respectively. However, 57, 64 and 17% of the actual amount of pesticides are overused for rice, cotton and maize, respectively. Moreover, the productivity effect of pesticides would be overestimated using Cobb-Douglas specification without incorporating a damage control agent.

Goosegrass is a worst grass weed in orchards and turf. The increased use of glyphosate for goosegrass control has led to the occurrence of many resistant populations. Although glyphosate has been used to control weeds for the past 30 years in China, few reports are available on glyphosate-resistant (GR) googegrass. In this study, we determined the GR level of 14 goosegrass populations from Chengdu and Guangzhou, China. Glyphosate only controlled 3.1 and 25.0% of the populations SL5 and SL1, respectively, at the dose of 1 680 g acid equivalent (ae) ha–1 at 14 days after treatment (DAT). In contrast, the susceptible population (XD1) was completely (100%) controlled. The resistant index (RI) of SL5 and SL1 were 5.1 and 4.5, and the RI for SL2, SL3 and ZC1 were 4.2, 3.2 and 2.6, respectively. The RI for other populations was range from 1.8 to 2.5. Under the dose of glyphosate at 1 640 g ae ha–1 at 10 DAT, shikimate accumulation in susceptible population XD1 was 17.6 and 16.4 times higher than SL5 and SL1, respectively. And the chlorophyll content in the plant leaf of populations SL1, SL2 and SL5 were decreased slightly ranging from 22.6 to 28.0. These results confirmed that the SL1, SL2, SL3, ZC1 and SL5 populations had evolved moderate resistance to glyphosate. This is the first report for the GR goosegrass populations confirmed in Chengdu, China.

Although studies argue that invasive species can cause biotic differentiation, some cases show that biological invasions actually decrease biodiversity through biotic homogenization. The concept of biotic homogenization through the invasion of a certain serious invasive plant species merit more studies. Hence, we used field surveys to quantitatively compare invasive populations of Solidago canadensis (SC) in China with the control sites (adjacent sites to SC present sites yet without the species) and SC native populations in the USA. We found that plant communities in SC invaded habitats shared similarities with those in SC native ranges. Bray-Curtis similarity clearly showed that the composition of plant communities in SC invaded habitats were similar to those in SC native ranges. Both in the native and introduced range, plant communities with SC present were characterized by SC being dominant, significantly lower species richness, α-diversity and β-diversity, as well as a decrease in the correlation coefficient between geographic distance and floristic similarities. SC favors fertile and moist loam habitat, while it dominated in various habitats in China, where more than 20 different dominants should have occurred. In conclusion, serious invasive species can quickly remodel and homogenize diverse communities by dominating them.

In this study, the effect of icariin, a flavonoid from the Chinese traditional medicine epimedium, on miRNA-21 of mouse developmental blastocysts in vitro and the development of preimplantation embryos were studied. The possible effective targets of icariin promoting preimplantation embryo development in vitro and anti-apoptosis were determined. The embryos were cultured in modified CZB medium (mCZB) as control group. The experimental group (Ica group) was supplemented with 0.6 μg mL-1 icariin. Mouse pronuclear embryos were cultured in vitro until blastocysts. The development rates of preimplantation embryos were observed. The total cell number, apoptotic cell number and the rate of apoptotic cells in blastocysts were analysed by the staining of Hoechst33342 and labeling of TUNEL and detected under a laser confocal scanning microscope. The miRNA-21 expression, the mRNA levels of pro-apoptotic Caspase3, and the target genes of miRNA-21: pro-apoptotic PTEN, anti-apoptotic Bcl-2 were detected by real-time RT-PCR. The results showed that percentages of morulaes and blastocysts in Ica group were both extremely higher than control group ((85.14±6.57)% vs. (72.04±11.58)%; (82.50±7.11)% vs. (66.80±11.70)%, respectively, P<0.01). The total cell number of blastocysts had extreme difference between Ica group and control group ((61.40±9.64) vs. (46.23±4.50), P<0.01). The apoptotic cell number and rate of apoptotic cells of blastocysts were both reduced in Ica group ((1.47±0.51) vs. (2.94±0.66); (2.40±0.27)% vs. (6.25±0.62)%, respectively, P<0.01). Compared to control group, addition of icariin into mCZB extremely increased the expression of anti-apoptotic miRNA-21 (P<0.01), down-regulated pro-apoptotic Caspase3 (P<0.05) and PTEN (P<0.01), up-regulated anti-apoptotic Bcl-2 (P<0.01). In conclusion, icariin could reduce the apoptosis, promote the embryo development in vitro by enhancing miRNA-21 expression to up-regulated anti-apoptotic genes and down-regulated proapoptotic genes. These apoptosis-related genes were regulated by miRNA-21.

The study was conducted in Zhifanggou Watershed, Shaanxi Province, China, to evaluate the effect of different vegetation types on hot-water extractable C, N and P fractions, with the aim to determine whether hot-water extractable fractions could be used as indicators of soil quality change in Loess Plateau. The six vegetation types established in 1975 were (i) Robinia pseudoacacia L., (ii) Caragana korshinkii Kom., (iii) Pinus tabulaeformis Carr., (iv) P. tabulaeformis-Amorpha fruticosa L., (v) R. pseudoacacia-A. fruticosa, and (vi) grassland. A cropped hillslope plot and a Platycladus orientalis L. native forest plot were used as references. The results indicated that the conversion of native forest to cropland resulted in a significant decline in the hot-water extractable C, N and P fractions. Hot-water extractable C, N, and P increased when cultivated land was revegetated, but after 30 years the amount of hot-water extractable C, N, and P in revegetated fields was still much lower compared to native forest. Hot-water extractable fractions increased more under mixed-forest than under pure-forest stands. Furthermore, there was a significant correlation between the hot-water extractable fractions and soil chemical and microbiological properties. The results showed that hot-water extractable fractions could be used as indicators of soil quality change on the Loess Plateau.

The Loess Plateau in China is one of the most eroded areas in the world. Accordingly, vegetation restoration has been implemented in this area over the past two decades to remedy the soil degradation problem. Understanding the microbial community structure is essential for the sustainability of ecosystems and for the reclamation of degraded arable land. This study aimed to determine the effect of different vegetation types on microbial processes and community structure in rhizosphere soils in the Loess Plateau. The six vegetation types were as follows: two natural grassland (Artemisia capillaries and Heteropappus altaicus), two artificial grassland (Astragalus adsurgens and Panicum virgatum), and two artificial shrubland (Caragana korshinskii and Hippophae rhamnoides) species. The microbial community structure and functional diversity were examined by analyzing the phospholipid fatty acids (PLFAs) and community-level physiological profiles. The results showed that rhizosphere soil sampled from the H. altaicus and A. capillaries plots had the highest values of microbial biomass C, average well color development of carbon resources, Gram-negative (G-) bacterial PLFA, bacterial PLFA, total PLFA, Shannon richness, and Shannon evenness, as well as the lowest metabolic quotient. Soil sampled from the H. rhamnoides plots had the highest metabolic quotient and Gram-positive (G+) bacterial PLFA, and soil sampled from the A. adsurgens and A. capillaries plots had the highest fungal PLFA and fungal:bacterial PLFA ratio. Correlation analysis indicated a significant positive relationship among the microbial biomass C, G- bacterial PLFA, bacterial PLFA, and total PLFA. In conclusion, plant species under arid climatic conditions significantly affected the microbial community structure in rhizosphere soil. Among the studied plants, natural grassland species generated the most favorable microbial conditions.

This study aimed to determine the characteristics of soil microbial community composition and its relationship with soil chemical properties during natural recovery in the Loess Plateau. The soil microbial community composition was analyzed by comparing the soil microbial phospholipid fatty acids (PLFAs) of eight croplands abandoned for 1, 3, 5, 10, 13, 15, 20, and 30 yr in the Dunshan watershed, northern Loess Plateau, China. The results showed that soil organic carbon, total nitrogen, soil microbial biomass carbon, and soil microbial biomass nitrogen significantly increased with the abandonment duration, whereas the metabolic quotient significantly decreased. The Shannon richness and Shannon evenness of PLFAs significantly increased after 10 yr of abandonment. Gram-negative, Gram-positive, bacterial, fungal, and total PLFAs linearly increased with increased abandonment duration. Redundancy analysis showed that the abandonment duration was the most important environmental factor in determining the PLFA microbial community composition. The soil microbial PLFAs changed from anteiso- to iso-, unsaturated to saturated, and short- to long-chain during natural recovery. Therefore, in the Loess Plateau, cropland abandonment for natural recovery resulted in the increase of the soil microbial PLFA biomass and microbial PLFA species and changed the microbial from chemolithotrophic to a more heterotrophic community.